The West Australian Integrated Marine Observation System (WAIMOS)
Chari Pattiaratchi (University of Western Australia)
West Australian Integrated Marine Observation System (WAIMOS) is a node of the Integrated Marine Observation System (IMOS) for Australia funded through the National Collaborative Infrastructure Scheme (NCRIS) and Education Infrastructure Fund (EIF) provide multi-disciplinary data sets. The main areas of interest for WAIMOS is the continental shelf and slope regions offshore from Fremantle and extending northwards to Jurien Bay in the south-west and the Kimberley and Bonarparte Gulf regions in the north. Within the south-west region there are important topographic features such as the Rottnest Island and Perth Canyon and the circulation is dominated by the southward flowing Leeuwin Current (LC) with the northward flowing Leeuwin Undercurrent (LU) beneath the LC and the wind driven Capes Current (CC) located on the shelf, particularly during the summer months. The IMOS infrastructure located in the SW region includes HF Radar (CODAR and WERA) systems) for surface current measurements at 2 different scales; Ocean gliders (Slocum and Seagliders) for subsurface water properties; continental shelf moorings (ADCP, thermistor and water quality loggers); passive acoustic sensors for whale monitoring; and, remotely sensed data products (SST and ocean colour). Example data collected from these instruments will be presented in relation to the understanding of different processes operating in the region. These include: (1) Interaction between the LC and CC. Here, the warmer, lower salinity southward flowing Leeuwin Current interacts with the cooler, higher saline northward flowing Capes Current creates a region of high horizontal shear and thus intense mixing; (2) Winter cascade of dense water along the continental shelf. The region experiences a Mediterranean climate with hot summers and cold winters. During the summer months the inner continental shelf waters increases in salinity due to evaporation. In winter as this higher salinity waters cool its density is higher than offshore waters and a gravitational circulation is set-up where the inner shelf water are transported as higher salinity plumes into deeper waters. In the northern region, the seasonal dynamics of the Leeuwin current initiation region has important implications for crossing boundaries as well as controlling the dynamics of the larger scale system.